Ester of isobutane-1,3-di-ol and method of making same



Patented Dec. 7, 1943 ESTER OF ISOBUTANE-L3-DI-0L AND METHOD OF MAKING SAME Gerald H. Coleman, Bartholdt C. Hadler, and Garnett V. Moore, Midland, Mich., assignors to The Dow Chemical Company, Midland, Mich., a

corporation of Michigan No Drawing. Application March 2th, 1940, Serial No. 325,008

14 Claims. ('Cl. 260-474) This invention concerns certain new esters and a method of preparing them.

The new esters herein claimed are 3-chloroisobutyl esters of organic carboxylic acids. They have the general formula:

wherein R represents a hydrocarbon radical or a substituted hydrocarbon radical. They are in most instances substantially colorless, high boiling liquids. They are useful as organic solvents and as chemical agents from which a variety of other organic compounds, e. g. mixed di-esters of isobutane-1,3-di-ol with two different organic acids, may be prepared.

We have found that a chloro-isobutyl ester having the above general formula is formed, usually together with a corresponding di-ester of isobutane-1,3-di-ol, by heating a metal salt of an organic carboxylic acid and 1,3-dichloroisobutane to a temperature at which they interact. The reactions which take place in this stage of the process are illustrated by the equations:

wherein R represents a hydrocarbon radical and M a metal. These two reactions appear to take place simultaneously even though the relative proportions of the two reactants be varied widely.

'Peculiarly, the yield of the diester (i. e. the orhydrogen chloride to form additional 3-chloroisobutyl mono-ester, thus increasing the yield of the latter. This reaction is illustrated by the equation:

Although this reaction of hydrogen chloride with the di-ester to form the 3-chloro-isobutyl ester may be carried out rapidly, the S-chloro-isobutyl ester product is relatively stable in the presence of hydrogen chloride and does not readily react with the latter. Accordingly, the di-ester formed by the initial step of reacting a salt of an organic acid with 1.3-dich1oro-isobutane need not be isolated prior to reacting it with hydrogen chloride. Instead, the crude reaction mixture comprising the 3-chloro-isobutyl ester and the corresponding organic di-ester, which is formed in the first stage of the process, may be treated directly with hydrogen chloride to convert a considerable portion ofthe organic diester into the desired 3-chloro-isobutyl ester and thus increase the yield of the latter.

In preparing a 3-ch1oro-isobutyl ester of a carboxylic acid, a mixture or a metal salt of the acid and 1.3-dichloro-isobutane is heated to a reaction temperature, preferably with agitation, in a closed reactor. Examples of metal salts of carboxylic acids which may be used in the reaction are the sodium, potassium, calcium, and barium salts of acetic, propionic, butyric, Valerie, caproic, crotonic, capric, undecylic, oleic, stearic, benzoic, cyclohexanoic, and cinnamic acids, etc. Alkali metal, e. g. sodium or potassium, salts of the organic acids are preferably used in the reaction.

The reactants may be used in any desired proportions, although the yield of the chloroisobutyl ester is usually highest when the two reactants are used in approximately equimolecular proportions; However, for purpose of in-' creasing the ease of stirring, we sometimes use a molecular. excess of the dichloro-isobutane reactant, e. g. we'use between 1.5 and 3 moles of 1.3-dichloro-isobutane per mole of the salt rephatic hydrocarbon, but the reaction may he carried out smoothly and at a satisfactory rate without use of such catalyst. Examples of catalysts which may be employed to promote the reaction are water; metallic copper; copper sulphate; copper acetate; and alkylamines, cycloalkyl amines and heterocyclic amines such as diethylamine, butylamine, cyclohexylamine, pyridine;

etc. By using copper or a copper compound to.-

gether with such amino compound as the catalyst, the reaction rate is increased markedly.

The reaction is preferably carried out in a bomb or autoclave at temperatures between about 170? and 225 .C., but lower or higher. re. action temperatures may sometimes be. used. After completing the reaction, the reactor may, if desired, be cooled and opened and the: reaction mixture be distilled to separate the ester products. When this is done, both a chloro-isobutyl ester of the carboxylic acid and a diester of the acid with isobutane-1,3-di-ol are usually obtained in substantial yield. If desired, the di-le'ster may then be re-heatedl in an autoclave with hydrogen chloride to convert a substantial proportion thereof to the chloro-isobutyl ester. The temperature required for this reaction is somewhat dependent upon the particular di-ester under treatment and the proportion of hydrogen chloride used, but is usually between about 100 and 200 C. After completing this reaction, the mixture may be distilled 'or otherwise treated to separate the chloro-isobutyl ester product.

However, when the chloro-isobutyl ester is de sired as the major product, it ismost convenient, after completing the initial reaction between l,3-dichloro-isobutane and' the carboxylic acid salt, merely to introduce hydrogen chloride to the reaction mixture and continue the heating, e. g. for between 0.5 and 2'hours. In practice hydrogen chloride gas is introduced into the re;

actor in amount corresponding to 0.5 or more of the chemical equivalent'of the metal salt react ant initially employed, but the hydrogen chloride is efiective in converting atleast a portion. of the oli-ester product into a corresponding chloro isobutyl ester regardless of'the proportion in which it is used. After completing the treatment with hydrogen chloride, the reactor is cooled and opened. The ester products are separated from the mixture in any of the usual ways, e. g. by distillation. The following examples illustrate certainiways in which the principleof the invention has been applied, but they are not to'be construed as 11m: iting its scope; r Example 1 A mixture of Bygram. mols of-'l,3-'dichloro-isobutane and 3,. gram .molsof. sodium acetate was heated with agitation in a bomb at a temperature A bomb. was char e with 0.5. ram 1,29 of IB-dit Y tane. wh h. has been rare: pared as in Example 1, and 0.49 gram mol of hydrogen chloride gas. The bomb was closed and heated, while rotating the same, at a temperature of 120-125 C. for 1 hour. It was then cooled and the charge was removed, washed with water and distilled. There .wasobtained 0.372 gram mol of 3-phloro-isobutyl acetate and 0,121 gram mol of unreacted 1,3.edi-acetoxyeisobutane.

Em p l 3 A mixture oi. equirn ec lar-amoup s o .316111 mot -isob a e nd s dium aceta e to whi a p oxi a y 0.4 pe en by w h oi y id ne ad. ee added as. heat d i a rotatin copper bomb at a tem eratu o 1 5 C- or 1 hour h b mb was th n. ce led and ga eous y ro en hlori e wa i tr u ed into the same n amount c spondin t p x mat ly f the 9: e u a ival of the s di m cetat a t a zly used. The bomb was then reheated to a temperature of 125 C. for 2 hours, after which it per. cent of. the sodium. acetate. had been consumed. ,Ehe, reacted. mixture, was. washed withwater d ried, and distilled, Therewere obtained.

was cooled and the charge was removed; The mixture was washed with water, dried and fractionally distilled to separate the ester products. There v were obtained approximately 14.8 mols of 3-chlor0-isobutyl acetate per mol of the 1,3-di-acetoxyisobutane product.

Example 4 A mixture of 5 gram ,mols of sodium propionate,

copper bomb at a temperature of 175 C. for 15 hours. The bombwas then cooled and the charge removed. The reactedv mixture was distilled to separate thev ester products. There were obtained 0.81 gram mol of 3-chloro-isobutyl propionate and 0.91 gram mol of Z-methyl-trimethylene glycol di-propionate. The 3-chlor'o-isobutyl propio-nate product was. a colorless liquid boiling at temperatures between 130 and'133 C. at mm. pressure, having the specific gravity of- 1.048 at 25 C./25 C'., and-having the index oi refraction n =1.4 33. It has the formula 2 a l-Q kQe e r e eegrqa a The Z-methyl-trimethylene glycol. di-propionate. is a colorless. liquid boilingiat 1303-131 C; at'20 mm. pressure, having the specificgravity.oi;1:.003r

at 25 C./25 C. and having, the index of tion n =1.425. Its formula is: i

. V CH3 I V O moom -o-em-tn-mh-o-tt-omcw Example A mixture of 5 gram 'mols of sodium butyrate, 5 ram mols of 1,3-dich1oro-isobutaneand 0.05 gram mol of pyridine was heated .in a rotating copper bomb at a temperature of, 175 C- for 15 hours. The bomb was then cooled and the charge removed. The reaction mixture was diluted with carbon'tetrachloride, filtered, and the filtrate was distilled to separate the ester products There were obtained 1.08 gram mols ofB-chloro-isobutyl butyrate and 0.79 gram mol of 2-methyl-1,3-tri-. methylene glycol dibutyrate. The 3-chloro-isobutyl butyrate product was a colorless liquid boiling at approximately 125-127 C. at 50 mm. pressure, having a specific gravity of 1.023 at 25 C./25 C., and having the index of refraction n =1.434. It has the formula:

CH3 c1cHT-H0Hr0 -oH2oHzoH3 The Z-methyl-1,3-trimethy1ene glycol di-butyrate product was a colorless liquid boiling at 135-136 C. under mm. pressure, having the specific gravity of 0.9807 at 25 C./25 C. and having the index of refraction n =1.439. It has the formula:

re a

Example 6 A mixture of 2 gram mols of sodium crotonate, 2 gram mols of 1,3-dichloro-isobutane and approximately 0.03 gram mol of pyridine was heated in a rotating copper bomb at temperature 175 C. for hours after which the bomb was cooled, the charge removed and the ester products were separated as in Example 5. There were obtained 0.537 gram mol of 3-chloro-isobut-yl crotonate and 0.421 gram mol of 2-methyl-trimethylene glycol dicrotonate. The 3-chloroisobutyl crotonate is a colorless liquid boilin at approximately 115-118 C. at mm. pressure and having the specific gravity of 1.057 at C./25 C. Its formula is:

CH: H ClCHz JHCHr-OCCaHs The 2-methyl trimethylene glycol dicrotonate is a colorless liquid boiling at 115-119 C. under 3 mm. pressure and having the specific gravity of 1.031 at 25 C./25 C. Its formula is:

CH3 0 H5CrC 'O-CHPH-CH OIC:4E5

Example 7 A mixture of 3.18 gram mols of sodium benzoate, 5.5 gram mols of 1,3-dichloro-isobutane and approximately 0.05 gram mol of pyridine was heated in a rotating copper bomb at 175 C. for 15 hours. The bomb was then cooled and the charge removed. The reaction mixture was distilled whereby there was obtained 0.602 gram mol of 3-chloro-isobutyl benzoate, a colorless liquid boiling at approximately 148-150 C. under 10 mm. pressure, having the specific gravity 1.142 at 25 C./25 C., and having the formula:

Example 8 *A mixture of 2.5 gram mols of sodium salicylate, 5 gram mols of 1,3-dichloro-isobutane and approximately 0.05 gram mol of pyridine was heated at atemperature of C. in a rotating copper bomb for 15 hours after which the bomb was cooled and the charge removed. The reactionmixture was distilled whereby there was obtained 0.832 gram mol of 3-chloro-isobutyl salicylate, a colorless liquid boiling at approximately 131-132 C; under 3' mm. pressure and having thespecific gravity of 1.202 at 25/25 C. The product has the formula:

' Example 9 A mixture of 0.74 gram mol of sodium cinnamate, 0.74 gram mol of 1,3-dichloro-isobutane and approximately 0.01 gram mol of pyridine was heated in a rotating copper bomb at a temperature of 175 C. for 15 hours. The bomb was then cooled and the charge removed. The reaction mixture was distilled, whereby there was obtained 0.215 gram mol of 3-chloro-isobutyl cinnamate, a colorless liquid distilling at approximately 147- 148 C. under 1 mm. pressure and having a specific gravity of 1.125 at 25 C./25 C. The formula for the product is:

By procedure similar to that illustrated in the foregoing examples we have also reacted 1,3-dichloro-isobutane with sodium oleate and obtained 3-chloro-isobutyl oleate which is a viscous, high boiling liquid.

Other modes of applying the principle of the invention may be employed instead of those explained, change being made as regards the method or compounds herein disclosed provided the steps or compounds set forth by any of the following claims or the equivalent of such stated steps or compounds be employed;

We therefore particularly point out and distinctly claim as our invention:

1. A 3-chloro-isobutyl ester of an organic carboxylic acid.

2. A 3-chloro-isobuty1 ester having the general formula:

CH3 Cl-CHf-lH-CHz- O--R vherein R. represents an aromatic radical.

3. A 3-chloro-isobutyl ester of an aliphatic carboxylic acid.

4. 3-ch1oro-isobutyl acetate.

5. 3-ehloro-isobutyl propionate.

6. 3-chloro-isobutyl salicylate.

7. The method of making a 3-chloro-isobutyl ester of a carboxylic acid which comprises reacting a metal salt of an organic carboxylic acid with 1,3-dichloro-isobutane.

8. In a method of making a 3-chloro-isobutyl ester of an organic earboxylic acid, the step of reacting an alkali metal salt of an organic carboxylic acid with 1,3-dichloro-isobutane.

9. In a method of making a B-chloro-isobutyl ester of an organicearboxylic acid, th step of reacting an alkali metal salt of an organic carboxylic acid with 1,3-dichloro-isobutane in the presence of-a catalyst.

10. In a method of making a 3-chloro-isobutyl ester of an organic carboxylic acid, the step of heating a substantially anhydrous mixture of 1,3-dich1-oro-isobutane and an alkali metal salt of an organic carboxylic acid at super-atmos pheric pressure to a reaction temperature betwee about 170 and about 225C.

11. The method which comprises heating a substantially anhydrous mixture of 1,3-dichloro isobutane and an alkali metal salt of an organic carboxylic acid at super-atmospheric pressure to" a reaction temperature between about 170 and about 225 C. and thereafter adding hydrogen chloride to the mixture and heating the mixture at super-atmospheric pressure to a temperature between about 100 and about 200 C. V

12. The method which comprises heating a substantially anhydrous mixture of 1,3-dichloroisobutane and an alkali metal salt of carboxylic acid at super-atmospheric pressure to a reaction temperature between about 170 and about 225" 0., thereafter adding hydrogen chloride, contin uing heating of the mixture at temperatures between 100 and 200 C., and separating a 3-chloro-isobutyl ester of the carboxylic acid from the reacted mixture.

- '13-. In a method of making a 3-chloro-isobutyl ester of an organic carboxylic acid, the step of reacting hydrogen chloride with a corresponding 

